Back Button
I guess I'd call it an "undocumented feature" rather than a bug, but I also find that there are two dummy URL's before the full window opens, so if I go back, I have to go back several steps, not just one.
Also, If change between boards, (e.g. Space to Geek) the last location in my "Go" list is described as Geek, but is actually the last Space window!
However, I've got used to the idiosyncracies of the thing...